Defect evolution during through-silicon via copper electroplating and methods for robust void-free filling

Void-free electroplating of copper in high-aspect ratio via structures is an important capability for achieving high-reliability through silicon vias (TSVs). In this study, the evolution of voids during the copper electroplating process for 6x55 μm TSVs is examined through staged electroplating experiments. Additionally, the transformation in void shape during the post-annealing process is investigated, which indicate void migration towards the TSVs sidewalls after annealing at 400
⁰
C. To achieve robust and void-free filling, we study the effects of applied current density and periodic pulse current waveforms on copper TSVs filling. Through the utilization of periodic pulse current waveforms, void-free filling is achieved with a 30% reduction in processing time compared to the direct current method.